Field of the Invention
Embodiments of the present invention relate to tool heads for use in a rotary cutting tool and to rotary cutting tools including such tool heads.
Background Information
EP 0 813 459 B1 provides an example of a known rotary tool. Rotary tools of this type are modular tools, in which the cutting head is insertable in a reversibly interchangeable manner into a carrier. For this purpose, a coupling is required between the cutting head and carrier. A coupling generally has stop surfaces which serve to transmit a torque between the cutting head and the carrier. Furthermore, clamping or centering surfaces are provided as further functional surfaces, via which the cutting head is oriented in an axially parallel manner relative to the carrier.
In the case of the coupling which can be gathered from EP 0 813 459 B1, the cutting head has, at the rear end thereof oriented toward the carrier, a coupling pin which is received in a coupling receptacle of the carrier. The coupling pin merges here via a flat head support surface, with which the cutting head comes to rest on a flat end support surface of the carrier. The coupling pin here has the stop surfaces and the clamping or centering surfaces. The coupling pin is therefore wound around by flutes from the webs as far as possible recesses, and both functional surfaces, i.e. the stop surfaces and the clamping surfaces, are arranged in the interior and do not extend as far as an outer circumferential surface.
EP 1 996 358 B1 discloses a further coupling point with a wound-around coupling pin, but in which flutes do not interrupt the winding therearound.
In addition to this wound-around type, couplings are also known, in which the wound-around coupling pin merely bears the clamping surfaces, but, by contrast, the stop surfaces protrude in the radial direction, with a step being formed, and reach as far as the outer circumferential surface. A non-wound-around coupling of this type can be gathered, for example, from US 2011/0318128 A1 and from U.S. Pat. No. 6,059,492. Said documents also disclose a dovetail-shaped configuration of the clamping surfaces, and therefore said clamping surfaces form an engagement from behind in order to ensure axial pull-out protection.
The applicant's DE 10 2012 200 690.7, which has not yet been published at the filing date, describes a coupling of the wound-around type, in which the coupling pin, as viewed in cross section, has an approximately rectangular basic shape and is cut by flutes. The transverse sections of the coupling pin here form the clamping sections, whereas the longitudinal sections of the coupling pin form the stop surfaces. The coupling pin is at the same time of overall approximately dovetail-shaped design. The coupling point is in the form of a self-centering and self-clamping, reversibly interchangeable coupling. No additional fastening elements, such as screws or the like, are provided for securing the cutting head in the carrier.
The production of a coupling pin of this type is associated with a certain outlay because of the dovetail-shaped configuration of the coupling pin and the different functional zones. There is also an acute angle at the transition between coupling pin and the flat head support surface because of the dovetail-shaped configuration, and this results in high stress concentration forces, in particular in the region of the stop surfaces.